MPS Options

[Bullet]

I can seem to get my 914 to not run Rich. I have checked Injector spray paterns, replaced cap,rotor, points, condensor,plugs, plug wires. and belive that my vacuum routing is correct. I question the integrety of the MPS. if i remove the vacuum hose that runs to it and clamp it off i get no change at all in performance. I was told by a co-worker that i should drill out the riviots and check to see if it is gummed up. I just removed it and am getting ready to take it apart, when out of curiousity I ohm checked the teminals and this is what i got : pin 8 - pin 10 350 ohms, pin 7 - pin 15 90 ohms. is this normal? does anyone know of any way to check the MPS. Or could any one do a quick ohm check on theese terminals to let me know if that is a correct reading? any help would be greatly apreciated.

[Jeff Bonanno]

a quote from pbanders site (MPS page):

"The LVT, aneroid cells, and full-load diaphragm are visible in the diagram. At idle, the MPS chamber pressure is much lower (approximately 16 to 18 in. Hg) than atmospheric pressure. This pressure differential across the diaphragm causes it to be pressed hard against the part-load stop. The aneroid cells are evacuated during manufacture, and are normally compressed (flattened) due to atmospheric pressure. At the low pressure in the MPS chamber at idle, they expand. As a result, the armature is driven out of the core, reducing the inductive coupling between the coils. The contact trigger pulse is minimally coupled to the output coil, causing the ECU to send a short injection pulse. However, at idle, the throttle position sensor turns on the idle circuit in the ECU, which lengthens the pulse and enriches the mixture independently of the MPS response. "

not sure if the injector pulse length is completely decoupled from the MPS circuitry at idle but from the above, it sounds like the ecu takes over based on the TPS position

jbb